This invention relates to key operated percussion devices such as pianos and, more specifically, to the hammer assemblies of such devices. A hammer assembly according to this invention comprises a hammer 40, hammer shank 30, shank butt 20, and knuckle 240.
A piano produces sound as a result of a complicated mechanical chain reaction which starts with the pianist depressing a piano key which in turn actuates a piano action associated with the key which in turn rotates a hammer assembly associated with the piano action which in turn strikes a piano string or strings to make sound.
More specifically, a depressed key 10 gives rise to motion of the damper head assembly (not shown), separating the damper head from the associated set of strings 35, setting the strings ready to accept vibrations. The depressed key 10 also actuates the piano action 15 thereby pushing or “throwing” the associated hammer 40 and hammer shank 30 into the associated set of strings or string 35. The hammer 40 strikes the strings, generating a piano tone. The piano action 15 then receives or “catches” the hammer 40 and hammer shank 30 after it strikes the strings 35 and rebounds back against the action 15. When the pianist releases the depressed key 10, the key 10 returns to the rest position, and permits the damper head assembly to return contact with the vibrating strings 35. The vibrations are absorbed by the damper head assembly, and the piano tone is terminated.
With a grand piano 45, a certain amount of kinetic energy is required when depressing a key 10 in order to move a hammer 40 as imparted by the piano action 15 to the integrated hammer shank (20 and 30). When a key 10 is depressed, the repetition base 70 is pushed upward pivotally about the repetition flange 90. The jack 50 is simultaneously moved upward pivotally about point 100 in the clockwise direction and pivotally about repetition flange 90 in the counterclockwise direction, resulting in a general upward motion. The jack 50 lifts the balancier 60, which also moves upward from double pivot motion, this time about the repetition flange 90 and point 110. The jack 50 raises the knuckle 80 along with the integrated hammer shank (20 and 30) thereby lifting the hammer 40 upwards towards the piano strings 35. The knuckle 80 also slides along the guide surface of the balancier 60. These both cause the hammer 40 to move upward by rotation about point 105 towards the set of horizontally stretched strings or string 35 associated with that key 10. The hammer 40 moves with “free rotation” powered by the knuckle 80 sliding along the balancier 60. The hammer shank 30 is further rotated and disconnects from the balancier 60 in order for the hammer 40 to strike the strings 35.
Likewise, with an upright piano 115, a certain amount of kinetic energy is required when depressing a key 10 in order to move a hammer 40 as imparted by the piano action 15 to the shank butt 20 and hammer shank 30. As the key 10 is depressed, the wippen 120 is pushed up to pivotally move upward, causing the jack 130 to move up together with the wippen 120. The jack 130 is pivotally arranged on the wippen 120. The hammer 40 is then pushed up by the jack 130 through the shank butt 20, and pivotally moves toward a set of vertically stretched strings or string 35. Then, as the jack 130 comes into contact with a regulating button 140, the jack 130 is prevented from moving up and loses contact with the shank butt 20. The hammer 40 and hammer shank 30 continue to move upwards, without contact with the jack 130, and are thus thrown into the string or strings 35 to create piano tone.
At this point, on both grand pianos and upright pianos, conventional wooden hammer shanks 30 bend somewhat before whipping around to strike the strings. This phenomenon can be verified by simple high speed photography of hammer motion resulting from practically every instance of piano playing. The more virtuosic the particular piano piece played, the greater the bending or deflection of the hammer shanks 30. This is because virtuosic piano pieces require greater key depression strength with faster key depression repetitions, which results in more forceful and more frequent hammer assembly rotations. As with all deflection motion, the greater the force applied on the body, the greater the deflection.
Since the energy absorbed by a bending of hammer shank 30 does not directly translate into the production of music, it is wasted energy or energy loss of the system. Thus, more key depression energy is required in order to produce music as a result of the bending of a hammer shank 30. Therefore, the elimination of hammer shank 30 deflection lowers the threshold energy requirement for the creation of sound. Hence the elimination of hammer shank 30 deflection results in a more responsive piano that requires less touch weight on the keys to play the piano.
The grand piano prior art consists of an integral shank butt 20 and hammer shank 30, hereafter known as an “integrated hammer shank”, made of wood, typically hornbeam or maple wood. The prior art does not consist of separate shank butt 20 and hammer shank 30 components. Prior art hammer shanks 30 come in one standard diameter or cross sectional area that can be thinned to reduce mass. The reduced mass is particularly required in the treble section because of the need to make the hammer rebound more quickly from the string. Prior art hammer shanks 30 are thinned on an increasing basis gradually as the pitch of the string or strings 35 associated with the particular hammer shank increases. For manufacturing efficiency, this thinning is not continuous but rather is stepped by three separate groups—“thin”, “medium”, and “thick”. “Thick” hammer shanks are not trimmed at all and are used on the bass end of the piano. Hammers 40 are glued onto the hammer shank end of the integrated hammer shank (20 and 30). The integrated hammer shank (20 and 30) is connected to a hammer shank flange 95 by a center pin. The shank flange 95 is attached to the shank rail on the piano. The deflection referenced above occurs in the integrated hammer shank (20 and 30).
The applicants have conducted experimental analysis on grand piano integrated hammer shanks (20 and 30) made of hornbeam wood in order to determine their average rigidity. An integrated hammer shank (20 and 30) was clamped tight and secure on the shank butt end while weight was applied at 4.00″ from the clamping point. A 4″ effective length was used as this length is typical for grand piano integrated hammer shanks (20 and 30). Deflection 250 was measured at 3.79″ from the clamping point. Deflection 250 from various weights was recorded. See FIG. 3 for a depiction of the setup used to quantify the rigidity of the prior art integrated hammer shanks (20 and 30). The results of the deflection experiment are summarized in the table below.
Prior Art Integrated Hammer Shank Rigidity Test
“Thick” HB“Medium” HB“Thin” HBAverageAverageAverageWeight AppliedDeflectionDeflectionDeflection(lbs)(inches)(inches)(inches)00001.00.0660.0600.0752.00.1320.1190.1513.00.1960.1770.2304.00.2630.2400.3115.00.3330.3070.3916.00.4120.3470.473
The relationship is linear, i.e. deflection 250 varies linearly in relation to the change in weight applied. Thus, the degree of deflection, which is inversely proportional to rigidity, of the integrated hammer shank (20 and 30) may be represented by a constant. In this case, the constant is given in the units of inches of deflection 250 per pound of weight applied and is determined by dividing the deflection number by the weight number listed above. The degree of deflection 250, defined as “deflectability”, of the hornbeam integrated hammer shank (20 and 30) going form thick, medium, to thin is 0.066 in/lbs, 0.060 in/lbs, and 0.077 in/lbs respectively. The standard deviation of these measurements is less than 0.0015 in/lbs in all cases. Note the smaller the deflectability measurement, the greater the rigidity of the integrated hammer shank (20 and 30). Also note that hornbeam wood has greater specific gravity than that of maple wood and is, thus, more rigid than maple wood. Therefore, hornbeam integrated hammer shanks (20 and 30) are more rigid than their maple counterparts.
The complicated mechanical chain reaction required to strike piano strings deeply affects the music generated by the piano. With most string instruments, the musician touches the strings directly with his hand or directly through a non-dynamic instrument such as a pick or a bow. Conversely, the pianist must depend on a series of mechanical actions, assembled from many small parts, to strike the strings. A pianist varies the speed, force, repetition, acceleration, timing, and other characteristics in near endless combinations when depressing and releasing keys in order to produce various piano tones to yield artistic piano music.
The preferred “feel” of a piano action has come into acceptance more from tradition rather than from methods associated with modern engineering and material science. In the early 1900's, manufacturers used the best available materials at the time, to practically produce high quality piano actions. Hardwood and felt were the primary materials used to produce piano actions at that time. For better or for worse, pianists, to this day, strongly prefer wood/felt actions simply because they deliver the feel consistent with what they grew up with, leading to the propagation of more wood/felt actions, leading to newer generations of pianists learning to play on wood/felt actions, leading to the same preference with new generations, and so on.
Relative to more modern materials, such as composites or plastics, wood is an inefficient raw material from which to manufacture piano action components. Wooden action pieces must be drilled to produce the holes required for pivotal connections and assembly with other action components. The hole-drilling process is a laborious and costly process as compared to the production of molded piano action pieces with holes accurately formed therein during the initial molding process. Also, the production of any finished wooden piece necessarily involves relatively large quantities of wasted material in the form of saw dust, which is inefficient and wasteful.
Wood is hydroscopic, i.e. wood swells or shrinks as its moisture content changes in response to the environmental. This can cause binding in the action. Additionally, after repeated occurrences, this causes compression of the wood leading to failure of the piano action component. For instance, wooden flanges often crack due to expansion from a rise in moisture content, as the screw crushes the wood in the flange where it is fastened to the rail.
Moreover, wood has different strengths in different directions, complicating manufacturing processes, also resulting in reduced manufacturing efficiencies. Additionally, wood has inferior rigidity and strength as compared to modern composites and plastics. In particular, rigidity and strength is of the utmost importance to the hammer assembly portion of the complicated mechanical chain reaction of a piano.
Finally, the lifespan of wooden piano action components is limited as compared to that of other materials such as composites or plastics because wood eventually crumbles into dust after a certain amount of environmental cycles. On the other hand, composite piano action components would have several times the life span of that of their wood counterparts and thus result in more efficient manufacture and maintenance of a piano.